This Saito 62 is swinging a CF 13 ~ 6 three blade at ~8400, 5.3 second laps on 63 foot lines. With a two blade 13-6 I would suspect you would end up with it choked down a bit further as the two blade would be easier for the engine to turn.
Way back when I first tried running a 56 I started with a 13-6 Bolly and a wide open Dixon intake. It ran OK but when the wind picked up it was doing about 90 at the bottom of the vert eight. Might be on the look out for any tendincy to wind up and don't hesitate to go up in pitch or to a 3 blade if your prop doesn't provide enough load.